From: Barnhart, Troy (TBarnhart@RCRH.ORG)
Date: Fri Sep 27 2002 - 14:00:16 EDT
take a look at the "mklv" command - the lv's are created in "raw" vs. "jfs,
etc."
these raw files can take up considerable space but are not reported
anywhere.
from the IBM Doco Library:
----------------------------------------------------------------------------
-------
Defining a Raw Logical Volume for an Application:
This procedure is used to define an area of physical and logical disk space
that
is under the direct control of an application rather than under control of
the
operating system and file system. The applications use character (raw) input
and
output rather than the block input and output of file systems, which require
more
software overhead. Bypassing the file system overhead enables applications
to
perform better. Raw logical volumes are most commonly used with database
applications because of their need for high performance. While there is
ordinarily
a significant increase in performance, the actual amount of the increase
depends
on the database size and the driver provided by the application.
----------------------------------------------------------------------------
-------
now, on one of my aix boxes i had the DBA put his data on top of my drives
built
with jfs. (I know it's not a "best practice" always, but i built the
filesystems
to match physical drive size. the oracle vg's are dedicated, so i build
them full.
i'm more space-limitation-conscious w/ my rootvg, though.)
but with a recent additional aix - the application vendor requires his
oracle
tablespaces to be datafiles on raw lv's.
But how can i see the "null space"???
combo of lslv and df-k ???
I'm sure someone has run into trouble being able to know how much space you
have
left...
troy
Troy Barnhart, Sr. Systems Programmer,
tbarnhart@rcrh.org
Rapid City Regional Hospital,
Rapid City, South Dakota, 57701
ph: 605-719-8068 / fax: 605-719-4206
-----Original Message-----
From: Wesley Joyce [mailto:Wesley.Joyce@uvi.edu]
Sent: Friday, September 27, 2002 11:41 AM
To: IBM AIX Discussion List; aix-l@Princeton.EDU; Barnhart, Troy
Subject: Re: actual space used.
Importance: High
I have posed a related question in the past. While browsing
www.aixgeek.org, I found this excerpt
Question: The "df" and "du" commands indicate that the file system is 50%
full, but you notice that the total size of all files, as given by "ls" is
greater than the size of the file system. How is this possible?
Answer: These are sparse files, where the size of the file is larger than
the amount of space it takes up. The file contains a large of "null
blocks".
If I remember correctly, Oracle reserves space in it's table spaces which
make the data files. Those reservation might be what is called "null
blocks". Wouldn't this help explain why the output of the df command and
ls is different? Obviously this isn't a solution but it helps me to
understand a little better. Maybe we should take this to an Oracle list?
At 05:23 PM 9/24/2002, Barnhart, Troy wrote:
>does anyone out there have a script or such that can tell how
>much space you system has?
>
>such as something that can take the data from a "df -k" plus
>the space occupied by the raw datafiles that oracle uses
>
>tia,
>troy
>
>Troy Barnhart, Sr. Systems Programmer,
>tbarnhart@rcrh.org
>Rapid City Regional Hospital,
>Rapid City, South Dakota, 57701
>ph: 605-719-8068 / fax: 605-719-4206
>
>
>
>
>---
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Wesley Joyce, Systems Administrator
Center for Administrative Computing (CAC), IT
University of the Virgin Islands
#2 John Brewers Bay, St. Thomas, USVI 00802-9990
(340) 693-1469 (voice) / (340) 693-1465 (fax)
http://www.uvi.edu
"If you can't explain it simply, than you don't know it well enough. -
Unknown."
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